Hillary Clinton's campaign just tweeted a chart that will make math majors cringe

Democratic presidential frontrunner Hillary Clinton's campaign
attempted to make an interesting point about gun regulations on
Friday. It ended up tweeting out an incredibly poorly designed
and ultimately confusing chart.

The chart appears to be based on the idea of a Venn diagram, a
very common chart used to illustrate the overlap between two
sets. Clinton's campaign seems to be trying to argue that there
is a big overlap between gun owners and Americans who support
background checks for gun purposes.

Unfortunately, the chart completely fails at the basic elements
of being a Venn diagram:

A Venn diagram of this type is useful for illustrating two
distinct sets that have some overlap. But in this case, that
isn't true — Clinton's two sets are "Americans" and "gun owners."

But she is presumably talking about American gun owners and their
support for background checks. That makes the second set a proper
subset of the first. As it is, the chart suggests that a large
number of gun owners are not Americans.

A better layout might have the first set be "Americans who
support background checks." Then, at least, we could be properly
looking at the overlap between two sets.

This isn't the first time a prominent Democratic politician has
messed up a Venn diagram. In his 2013 State of the Union,
President Barack Obama showed a chart comparing US and Chinese
investment in solar energy,
similarly abusing the Venn diagram format.